Impacts of Urbanization on Vector Biology and Transmission of Dengue in China. Dengue is a major public health problem in southern China. In recent years, the epidemic interval of Dengue outbreaks in southern China has become shorter and the epidemic area is expanding. Because Dengue epidemics coincide with rapid urbanization in China as a result of economic development, it has been suggested that urbanization creates favorable conditions for the survival and reproduction of Dengue vectors and for the transmission of Dengue virus. This application tests the central hypothesis that environmental changes resulting from urbanization affect the biology and vectorial capacity of Aedes albopictus, the major Dengue vector in southern China. We will further examine the molecular epidemiology of the Dengue virus in urban areas for major outbreaks in Guangzhou city in the past two decades. The long-term goal of this research is to determine the mechanisms of Dengue epidemics in urban environments and to develop effective prevention and control methods. We have designed the following two specific aims. First, we will determine the impact of urbanization on the larval and adult ecology of Aedes albopictus mosquitoes, the sole Dengue vector in the Guangzhou area where the present study will be conducted. This aim will test the hypothesis that urbanization creates favorable conditions for the survivorship and development of Aedes albopictus larvae and subsequently, increases the abundance of the Dengue vector. Second, we will determine the transmission patterns of Dengue virus in urban environments. This aim will test the hypothesis that Dengue outbreaks are associated with the introduction and circulation of new serotypes or genotypes of Dengue virus, and that vector competence of Ae. albopictus varies among Dengue viral serotypes and genotypes, and thus the most favored DENV serotype/genotype may become the epidemic type. The proposed research takes advantage of the unique Dengue epidemiological and vector population situations in Guangzhou, China where frequent Dengue outbreaks have occurred and Ae. albopictus is actively breeding in the urban environment. This research will significantly enhance our understanding of Dengue transmission in urban areas, and contribute to the development of effective surveillance and control programs of Dengue in China.